Advice from the Help Desk of the UC Master Gardener Program of Contra Costa County
Client's Request: I purchased a Yellow Rainbow Beefsteak Tomato Plant at your annual sale in Walnut Creek this year. The plant has grown quite big and has about four tomatoes on the plant. They have stayed about the same size for about two weeks now and are not turning yellow — they are green. I have used organic tomato fertilizer, but it has not helped. Any suggestions?
It's hard to know why your tomato has been so slow to produce ripe tomatoes. However, Yellow Rainbow Beefsteak tomatoes are one of the slower tomatoes to start producing—some websites call them “fall producers”. The typical time for the plants to start producing is about 90 days from the time the seedlings go into the ground, so it does seem that your plant is a bit late. One possibility is that the soil where it is planted had excessive nitrogen fertilizer. When there is excess nitrogen, tomato plants often produce abundant foliage but set very few tomatoes. Next year, you might want to do a soil test before you plant your tomatoes. You can purchase an inexpensive home soils test kit at a nursery or big box store. The kit typically allows you to test levels of three principal nutrients—nitrogen, phosphorous and potassium (N, P, K). N is used by plants to produce green foliage; P helps with fruit production and K helps with roots and the overall well-being of the plant. Then use fertilizers only as needed to address any nutrient deficits.
You indicated that you used an organic tomato fertilizer. That likely included some amount of all three nutrients (and possibly other micro-nutrients such as calcium). If the plant was already growing well, it probably didn't need more nitrogen. Applying a fertilizer that added only phosphorous might have done the job. Also, you didn't say when you applied the fertilizer, but we are guessing you might have added it to help spur fruit production. If you applied it before the four tomatoes set, the fact that you now have those tomatoes on the plant may be a sign that the fertilizer application did help. As for the slow growth of the size of the tomatoes and their being slow to ripen, I think you just need to be patient. If is not uncommon for heirloom tomatoes to take several weeks to mature. I waited about six weeks after fruit set for tomatoes on one of my plants this year to finally grow to an appropriate size and ripen.
Tomatoes don't need to have insect pollinators to set fruit. Rather, the flowers are typically pollinated by wind action. If you have flowers on your plant that have not yet set fruit, try to duplicate the wind effect by gently shaking the plants once or twice a day, preferably mid-morning. Also, it may be helpful for you to know that tomatoes usually don't set fruit when daytime temperatures are more than 85 to 90 degrees. It's been somewhat cooler throughout our county in recent days (but not the last several days when this was edited and updated for posting) and hopefully, you may have had some additional fruit set then. But it's about to get hotter again for the next several days (or more likely cool again thank goodness). By early week when this blog is posted, it's supposed to be cooler again. Hopefully, at that time some additional tomatoes will set, particularly if you remember to shake the plant occasionally.
One final thought, keep track of how well all of your tomato plants produce and how much you enjoy their flavor. I typically try to plant at least one variety that has been a reliable producer in prior years to make it more likely that I'll get a steady supply of tomatoes. I re-plant slow producing varieties again only if I really thought their taste was outstanding and worth the wait and low production rate.
Hope you soon have some tasty tomatoes to harvest.
Help Desk of the UC Master Gardener Program of Contra Costa County (tkl)
Notes: Contra Costa MG's Help Desk is available almost year-round to answer your gardening questions. Except for a few holidays (e.g., last 2 weeks December), we're open every week, Monday through Thursday for walk-ins from 9:00 am to Noon at 2380 Bisso Lane, Concord, CA 94520. We can also be reached via telephone: (925) 608-6683, email: email@example.com, or on the web at http://ccmg.ucanr.edu/Ask_Us/. MGCC Blogs can be found at http://ccmg.edu/HortCoCo/ You can also subscribe to the Blog.
Advice for the Home Gardener from the Help Desk of the
UC Master Gardener Program of Contra Costa County
MGCC Help Desk's Response: Thank you for contacting the UC Master Gardener Program Help Desk with your questions. I know the list of available tomato seeds and seedlings can be overwhelming.
Unfortunately, given our area each area can have lots of micro-climates. So we cannot tell you exactly which variety will grow best in your yard. That is highly dependent on your individual circumstances (are you planting in pots, raised beds, the amount of sun, temperature, disease). Your best information on how individual varieties will perform is likely from your successful tomato-growing neighbors.
There is some good information about heirloom tomatoes though. The scientific definition of an heirloom tomato is an open-pollinated variety that will make fruit identical to the parent. This means if you save seeds from your tomatoes you would expect to be able to produce the same fruit year after year. There is disagreement on how old a variety has to be to be considered an heirloom with some saying at least 50 years and others saying at least 100 years. Here are some links to articles written by nearby Master Gardener organizations which discuss heirloom tomatoes in further detail. In addition, if you want to save seed yourself you might look over the website for Seed Savers Exchange.
If you look through our list of tomatoes for our Great Tomato Plant Sale this year, you can see there are lots of different heirloom tomato varieties. It does appear that only one is a determinate variety (Black Sea Man, a slicer). As you likely know, determinate tomato varieties grow in more of a bush form than a vine and tend to set fruit all at once and then decline. For older varieties, most are likely going to be indeterminate. If you look through the offerings on Seed Savers, only 9 out of their 82 heirloom varieties appear to be determinate. You likely have found these lists already but below are the links to our descriptions of all our varieties and the shopping list to make it easier to find what you want the day of the sale.
Thank you for contacting us with your questions. We are very excited to see you for our MGCC tomato sale either on March 30th in Walnut Creek, April 6th in Richmond, or April 13th in Antioch.
Help Desk of the UC Master Gardener Program of Contra Costa County (SES)
Note: UC Master Gardeners Program of Contra Costa's Help Desk is available almost year-round to answer your gardening questions. Except for a few holidays (e.g., last 2 weeks December), we're open every week, Monday through Thursday for walk-ins from 9:00 am to Noon at 2380 Bisso Lane, Concord, CA 94520. We can also be reached via telephone: (925) 608-6683, email: firstname.lastname@example.org, or on the web at http://ccmg.ucanr.edu/Ask_Us/. MGCC Blogs can be found at http://ccmg.ucanr.edu/HortCoCo/ You can also subscribe to the Blog.
Help for the Home Gardener from the
Contra Costa Master Gardeners' Help Desk
The client bought 8 different tomato plants from the CCMGs' "Great Tomato Plant Sale". They are withering and dying. The client had previously purchased tomato plants from Navlet's Nursery; she reported that those plants did pretty well. The client observed that the growing season last year and this year were quite different. Each plant was a different variety but each died in a similar way. The plants are in two raised beds, 4' x 8' x 12”. The plants were transplanted from the original containers into gallon pots for two weeks while the bed was being prepared. Each plant was mounded and a base formed around the plants. The tomatoes were watered twice per week, in addition the tomatoes were fed once. The plants did well at first and then one by one they withered and died. The client had recently read about black walnut trees affecting tomatoes adversely, and they wondered if Master Gardeners had more information on that issue. The client has two black walnut trees in close proximity to the raised beds. These trees are in the neighboring yard.
Master Gardener's Response:
The proximity of the black walnut trees to your yard could certainly be contributing to the distress of the tomatoes. However, if the black walnuts are the sole problem, it's hard to understand why you had better success with your tomatoes last year than you've experienced this year. So there may be some other factors at work. We'll first give you some information about how black walnuts affect tomatoes (and certain other plants) and then desccribe some other possible causes for the decline of your tomatoes.
Black Walnuts and Tomatoes: As you noted in your email, black walnut trees produce a substance (called juglone) that is toxic to some plants, including tomatoes. Most of the toxic chemicals accumulate within the drip line of the tree (the area measured from the trunk to the outer reaches of its branches), but some effects of the chemical can extend beyond the drip line to a distance of 50 to 80 feet from the tree. If your tomatoes were planted within the drip line of the walnut trees, the toxic effect of the juglone may be the cause of the decline of the tomatoes (or at least a contributing factor). If the trees are more distant from the tomatoes, it is less likely that juglone is the problem, unless the toxic substance has been introduced into your garden area in some other manner—for example, from the debris from the trees blowing into the garden area or composting tree debris and spreading it in the garden.
"Plants sensitive to juglone may be stunted, have yellow or brown, twisted leaves, exhibit wilting of some or all plant parts, and die over time. Often, the vascular (i.e., water-conducting) tissue of affected plants will be discolored. Symptoms may occur rapidly, even within a few days after sensitive species are transplanted into a walnut tree's root zone. Alternatively, some plants may survive for years near a young walnut tree, but will wilt and die as the tree increases in size."
You can find more information about black walnuts and how they affect tomatoes and other sensitive plants at the Wisconsin Cooperative Extension website cited above and in the Washington State University fact sheet at http://bit.ly/1mwaq3A
Other Possible Causes: If your tomatoes are outside the drip zone of the trees, and you aren't aware of other ways that the trees may have contaminated your garden area, you might want to consider other possible causes.
Given that you had better success last year with the tomatoes you purchased at Navlet's, the problem this year may be connected with the varieties of tomatoes you tried to grow. Most of the tomatoes sold at the CCMG tomato sale are heirloom variety tomatoes. The ones you purchased last year were likely hybrid varieties which are common in commercial nurseries. If successfully grown, heirloom tomatoes often give you a better flavor than many hybrid tomatoes. Also, if you save seeds from a heirloom variety, the seeds will produce the same variety of tomato plant while seeds saved from a hybrid will not reliably grow the same plant variety in future years. The downside is that many heirlooms have less disease resistance than hybrid tomatoes.
Some common plant diseases that affect non-resistant tomato varieties are caused by soil borne pathogens that build up over the years in the soil. To minimize the chances that such pathogens will be present, crop rotation is a must. If you planted your tomatoes in the same spot as last year, then such problems are more likely to occur. It is best to use at least a three-year crop rotation cycle and not plant tomatoes (or other members of the same plant family such as peppers, potatoes, and eggplant) more than two years consecutively in the same garden bed and not plant other solanaceae plants (egg plant, peppers, potatoes, etc.) in the other years.
If you plan to try growing tomatoes again in the same garden area, and you are unable to practice crop rotation, be sure you buy or grow tomatoes that have some disease resistance. As mentioned above, you are most likely to find disease resistance in hybrid varieties. The plant label or seed package of disease resistant varieties will be labeled with codes for the diseases for which some resistance exists. Here's a list of the Codes and the tomato disease represented by each of the code letters:
Tomato disease resistance codes:
|F||Fusarium Wilt||T||Tobacco Mosaic Virus|
|FF||Fusarium, races 1 and 2||St||Stemphylium
(Gray Leaf Spot)
races 1, 2, and 3
Most varieties will only be resistant to some of these diseases. Look particularly for resistance to verticillium and fusarium wilt which are common in our county. Nematodes can be a problem also. The UC publication at http://www.ipm.ucdavis.edu/PMG/GARDEN/VEGES/tomato.html may possibly help you identify what disease could be affecting your tomatoes. Providing us with a sample and/or pictures would help us assist you.
If you suspect that soil borne diseases could have been the problem, perhaps next year you might try growing an heirloom tomato variety in a container, using a purchased soil mix which is unlikely to contain soil borne diseases. The purchased soil mixture in the container would also be unlikely to be contaminated with juglone, particularly if you position the container as far as possible away from the black walnut trees and keep any debris from the trees from falling into the container. If you decide to try growing a tomato in a container, use a container that is at least 16 inches deep. Cherry tomatoes or other varieties that produce smaller sized tomatoes usually do well in containers. “Determinate” varieties also do better than “indeterminate” varieties in containers. Look on the plant labels or seed packages to find determinate varieties. (We sell many determinate varieties at our annual tomato plant sale.)
Here's hoping that next year's varieties will prove fruitful and tasty tomatoes.
Contra Costa Master Gardeners' Help Desk
Editor's Note: The CCMG Help Desk is available year-round to answer your gardening questions. Except for a few holidays, we're open every week, Monday through Thursday from 9:00 am to Noon at 75 Santa Barbara Road, 2d Floor, Pleasant Hill, CA 94523. (map) We can also be reached via telephone: (925) 646-6586, email: email@example.com, and we are on the web at http://ccmg.ucanr.edu/. "Ask a Master Gardener" help tables are also present at many Farmers Markets as well as at the CCMG's "Our Garden" programs (map). See the CCMG web page for details/locations./span>